Targeted treatment of the most mollusc-riddled parts of a field has taken a step closer, thanks to an innovative research programme that tags and tracks grey field slug populations.

AHDB-funded PhD student Emily Forbes in the UK has been hot on the ‘slime trail’ of these major crop pests for the past three years. Based at Harper Adams University (HAU), she uses radio-frequency identification (RFID) tag technology, originally developed to track cattle, to monitor slug movement in commercial fields and explore options for more precise control.

Radio-frequency identification (RFID) tags can be injected into slugs to monitor their movements in the soil.

Emily said: â€œSlugs need to shelter from the sun; itâ€™s why they prefer to feed at night and shelter underground during the day. RFID tags reveal what slugs get up to, no matter where they hide.â€

The tags, which are about the size of a grain of rice, were injected into slugs. To make sure tagging did not change the slugsâ€™ behaviour, a laboratory experiment was set up to monitor their movements.

Video tracking found that the slugsâ€™ routines did not change, compared with non-tagged slugs. This finding gave the green light for the approach to be used to record natural slug activity in the field.

The PhD focused on the distribution of slugs across a field. In particular, Emily looked to define what causes slug populations to develop in distinct patches. An RFID scanner, which operates in a similar way to a metal detector, was swept over the ground regularly to map the whereabouts of tagged slugs.